[Ronja] IR vs Visible

[Gullik Webjörn]

Si rolls of above 900-1000 nm, for 1300-1600 you use GaAs. One way to handle
eye safety is to have
a negotiation protocol, where the laser runs with fill power, bur very low
duty cycle. Once communication
is established the duty cycle goes to 100 %. If the link fails, due to the
RX not seeing the TX, the negotiation
protocol is entered, lowering duty cycle below 1%

The result is that a bird or human getting into the optical path will lower
the energy so the beam will still
be eyesafe, until both units see each other with proper levels, meaning
there is nothing in the path.

Remember, police laser speed guns with watts of power are considered eyesafe
due to the low duty cycle.

Gullik
  -----Ursprungligt meddelande-----
  Från: ronja-bounces+gullik.webjorn=flysta.net at lists.pointless.net
[mailto:ronja-bounces+gullik.webjorn=flysta.net at lists.pointless.net]För
Pramod yaduvanshi
  Skickat: den 3 mars 2008 02:57
  Till: Twibright Ronja
  Ämne: [Ronja] IR vs Visible


  In IR Photodiodes will have a better response too!! since Silicon PIN
diodes have higher responsivity at IR frequencies ..am not sure if there are
Lasers and PIN available at a 1300 0r 1500 nm !! If there are then they will
be eye safe and can pump in more power unlike 850nm !! Does any one know of
some cheap Lasers and diodes in this band? 1300/1500nm?

  PK Yaduvanshi


  On 03/03/2008, eldis111 <eldis111 at seznam.cz> wrote:
    Is there reason not-to stay in IR? Only advantage I can think is easier
aiming..
    We installed many IR (professional) FSO, it is even faster than making
radio link (at least around 10GHz).
    Higher wavelength => better SNR due to losses in atmosphere and
interference from other sources.
    But there might be another reasons.. So, what is your opinion?

    eldis


    > Everything is fine... if you stay in the IR spectrum.
    > if someone could find visible light high power VCSELs, that would be
fine...
    > Bye,
    > Martin
    >
    > eldis írta:
    > > As Gullik says, VCSEL are much better than ordinary laser,
    > > just look at google.
    > > To me, it seems that VCSEL combines good things from laser and led
into
    > > one package.
    > >
    > > eldis
    > >
    > >
    > >
    > >> What is crappy about VCSEL?s?
    > >>
    > >> To me they seem ideal, circular beam, no or very little
    > >> astigmatism, low threshold current, good efficiency,
    > >> fast ( ghz) relatively robust, low cost.
    > >>
    > >> Why do you not like them?
    > >>
    > >> Gullik
    > >>
    > >> -----Ursprungligt meddelande-----
    > >> Fran: ronja-bounces+gullik.webjorn=flysta.net at lists.pointless.net
    > >>
[mailto:ronja-bounces+gullik.webjorn=flysta.net at lists.pointless.net]For
    > >> Gyurko Martin
    > >> Skickat: den 1 mars 2008 22:58
    > >> Till: Twibright Ronja
    > >> Amne: [Ronja] vcsel-s retail
    > >>
    > >>
    > >> Hi!
    > >>
    > >> For those who want these crappy lasers:
    > >>
    > >> http://www.roithner-laser.com/VCSELs.htm
    > >>
    > >> May them work for you.
    > >>
    > >> Martin
    > >>
    > >>
    > >>
    > >
    > >
    > >
    >
    > --
    > Twibright Ronja mailing list http://ronja.twibright.com
    > Ronja at lists.pointless.net
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    >
    >
    >

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